Lens distortion issue

[chazfest]

Hi,

Can I apply lens distortion in Houdini?

The reason being that I've set up and tracked a shot in Nuke using the 'CameraTracker' node, before which I undistorted the lens.

So I've used the in built 'Modeler' node to create rough location geometries, however, these are of course all tracked to the undistorted lens/camera.

Is there anything I can do in either Nuke or Houdini to make this workflow...work?

Hope this makes sense

Thanks in advance.

Chaz

[brianburke]

Hi,

Can I apply lens distortion in Houdini?

The reason being that I've set up and tracked a shot in Nuke using the 'CameraTracker' node, before which I undistorted the lens.

So I've used the in built 'Modeler' node to create rough location geometries, however, these are of course all tracked to the undistorted lens/camera.

Is there anything I can do in either Nuke or Houdini to make this workflow...work?

Hope this makes sense

Thanks in advance.

Chaz

standard workflow is to render your cg out at the undistorted resolution to match the undistorted plate and then apply the distortion to your cg in nuke. a copy of the 'lensdistortion' node you used to undistort your plate with 'undistort' checked off should do this perfectly.

gl dude.

[chazfest]

standard workflow is to render your cg out at the undistorted resolution to match the undistorted plate and then apply the distortion to your cg in nuke. a copy of the 'lensdistortion' node you used to undistort your plate with 'undistort' checked off should do this perfectly.

gl dude.

Thanks for the reply dude.

That sounds like a plan, the only thing is, I'll obviously be without any kind of scene geometry that way as the stuff from Nuke evidently doesn't line up, so it'd be a bit of a guessing game. I assume even my point cloud would export from Nuke as an undistorted point cloud too?

Hmmmmmm...

[LaidlawFX]

You can do lens distortion in houdini, similar to maya as a shader. So you could figure that out. It is the equivalent of writing a mental ray lens shader as far as I understand, since there are no off the shelf lens shaders for houdini it's not very practical. But maybe knowing you can do it, you can dig around to find more info on it, but as was said the workflow should not require you to do that. Also to spend the time to figure it out is way more of a pain than just doing another workflow to avoid this solution.

Edited April 9, 2011 by LaidlawFX

[brianburke]

Thanks for the reply dude.

That sounds like a plan, the only thing is, I'll obviously be without any kind of scene geometry that way as the stuff from Nuke evidently doesn't line up, so it'd be a bit of a guessing game. I assume even my point cloud would export from Nuke as an undistorted point cloud too?

Hmmmmmm...

everything should line up ok. the point cloud should == your undistorted plate.

you're tracking the undistorted plate right? that's essential.

Edited April 9, 2011 by brianburke

[chazfest]

everything should line up ok. the point cloud should == your undistorted plate.

you're tracking the undistorted plate right? that's essential.

Yes, I should have mentioned. I am tracking the undistorted plate.

Thanks for the heads up guys, I thought it was going to be a lot more complicated than it actually was! I just exported the undistorted clean plate from Nuke as an image sequence and swapped the current/previous Houdini background image out for it. As you said, everything now lines up nicely

Thanks for the help guys!!